A sexual method, where the male ejaculates in the females anus, in which the female pushes it out along with solid waste. The 'Nutter' means "bust a nut", and 'Butter' is the product of the faeces, and semen mixing together.

person1: "dude, it was so hot, i gave her the hottest Nutter Butter.
person2: " that sounds awesome, what colour was it?"